Fuel control valve



R. W. DE LANCEY FUEL CONTROL VALVE Filed April 15,- 1942 T m 0 M f M 7fl L L m w a Sept. 26, 1944.

- lNVENTOR 640w M DEZANCE'K ATTORNEY Patented Sept. 26, 1944 FUELCONTROL VALVE Ralph W. De Lancey, Mcriden, Conn, assignor to The MillerCompany, a corporation of Connecticut Application April 15, 1942, SerialNo. 439,017

1 Claim.

The present invention relates to fuel control valves, and is moreparticularly directed toward valves for controlling the flow of liquidfuel to burners of the type which employ a pilot flame.

It has heretofore been customary tosupply a limited amount of fuel tosupport a pilot flame, this limited flow being regulated by movingnearly to the closed position the valve member which also controls thehigh fire; In some instances the control valves have been arranged sothat the pilot valve is operated entirely independently of the maincontrolvalve stem. In all these cases, however,-the liquid for the pilotvalve has flowed through a valve opening which was submerged asubstantial distance below the liquid level in the constant level valve.

It is important that excess fuel should not be burned to maintain apilot, for such excess fuel is not only wasteful of the fuel, but mayresult in heating the furnace unnecessarily and in the more rapidformation of carbon which tends to put out or extinguish the pilotflame. The amount of fuel furnished the pilot must not be below anamount sufficient to maintain combus tion, otherwise the pilot goes out.It is thus apparent that for satisfactory pilot operation a rathercritical flow rate is necessary. When an attempt is made to control theflow of this amount of fuel through a hole or opening at or adjacent thevalve seat, as is usual in this art, experience has shown that pilotoperation was likely to become impaired by reason of clogging of thevery small opening necessary for the limited flow of fuel. When thepilot goes out the burner stops operation and must be serviced before itcan be restored to operation.

According to the present invention the fuel required for pilot operationis permitted to flow through a passage of fixed unvarying limitingdimension, in a predetermined and preferably unvarying position relativeto the surface of the liquid in the constant level valve. This makes itpossible to avoid all irregularities arising from movement of parts.Furthermore, according to the present invention the metering opening forthe fuel is placed just below the surface of the liquid in the constantlevel valve so that it is always submerged, and this hole can thereforebe made a great deal larger than the hole of equivalent flow ratesubmerged a substantial distance below the surface of the liquid.

The accompanying drawing shows, for purposes of illustrating the presentinvention, two embodiments in which the invention may take form, itbeing understood that the drawings are the same.

In the drawing:

Figure 1 is'a vertical sectional view througha combined constant leveland metering valve structure, and wherein the metering valve isprovidedwith the control for low or pilot flame;

Figure 2 is a perspective view of the valve stem of Figure l at anenlarged scale; and

Figure 3 is a fragmentary sectional view illustrating a modified form ofconstruction.

The present invention may be used with any form of constant level valveconstruction. In the form shown in Figure 1 the valve has a reservoirl0, inlet valve mechanism, indicated generally at H, which is under thecontrol of a plunger 12 adapted to press down on the inlet valve stem toclose the same.

A liquid displacement element l3 made of a lightweight alloy, such asaluminum and magnesium, or a plastic block, is secured to the long arm Mof a'lever i5 pivoted at [6 on abridge ll fixedly secured within thereservoir by screws l8 passed into lugs l9 formed in the reservoirwalls, and aligned by lugs 20 entering between lugs 2| and 22 formed inthe reservoir walls. The element I3 is so located that at the desiredliquid level to be maintained it has a partial submersion volume Vsomewhat less than the total volume so that it is buoyed upwardly andhas less apparent weight. The short arm 22 of the lever l5 carries anadjustable screw 23 adapted to enage a short lever 24 pivoted at 2-5 andresting on the plunger l2. The weight I3 is connected by aslopin link 26with a lever 21 pivoted at 28 to the bridge and carrying an adjustablecounterweight 29. The parts carried by the bridge may be assembled as aunit and secured in place.

The dimensions and mass distribution of the system are such that at apredetermined level of liquid the entire system is in balance and whilethe screw 23 is in contact with the lever 24 no pressure is exerted toclose the valve. Any increase in liquid level will submerge more ofweight l3 and increase its buoyancy so that it contributes less turningmoment to the system, whereupon the counterweight predominates andpressure is applied by screw 23 on lever 24 to depress the plunger l2 ofthe valve.

The receptacle is provided with an outlet valve seat 30 whichcommunicates through a passage 3| with the burner in the usual manner.The valve seat 30 cooperates with a valve stem .32 which is adapted tobe moved from full closed position against the valve seat to full openposimetallic thermostat 33 under the influenceof a remote control heater34. A manually operated valve may be used if desired. The valve stem 32is tubular and has a vent 35 above the level of the fuel as usual.

The valve stem 32 is provided with a small horizontal opening ordrilling 36 placed at such an elevation relative to the valve seat as tobe slightly below the level at which the constant level valvemechanismmaintains the liquid. For example, the hole produced by a drill .026inch in diameter and approximately 3%; of an inch below the oil levelwill provide a flow of 1.0 to 1.4 cubic centimeters per minute. Wherehigher pilot flow rates, such as 3 /2 to 11 cubic centimeters per 'letpassage 40 has a seat ll cooperable with the valve stem 42 of usualconstruction and adapted to move from full open to full closed positionto control the flow of fuel for high fire. A branch passage 43 extendsupwardly to a threaded seat 44. A plug-like member 45 is adapted to bethreaded into this seat. Thisplug-like member is tubular, as indicated,and has an opening 46 similar to and for the same purposes as theopening 36 in the valve stem. With this arrangement no change whateveris made in the structure of the valve for controlling high fire andminute are employed, the hole size and depth will be. altered to supplythe necessary flow. With an appropriate arrangement the flow rate may bekept within the critical flow rate for the bumer to be supplied over.very long periods.

It will be noted that this hole is in the region where the oil is leastcontaminated by dirt and foreignmatter, the latter settling always tothe bottom of the receptacle. There is therefore very little likelihoodof any dirt entering the hole. The hole is very short and as itcommunicates with the vent passage there is no likelihood of an airbubble interfering with the flow of the oil.

'With'this form of construction the complete valve device is assembled,flow rated and adjusted at the factory. Exhaustive tests have shown thatwhen these valves are employed with pot type burners requiring thelowest flow rate mentioned, pilot failure is reduced substantially tothe vanishing point. It is impossible to tamper with the pilot flow rateand it is also impossible for the Serviceman to alter the flow rate inthe existing structure. 'Where it is necessary to obtain a differentflow rate the valve stem must be completely removed and one withdifferent sized opening or differently located opening substituted.

In the arrangement shown in Figure 3 the outthe pilot control is throughthe independent communicating outlet having the metering opening. Themember 45 may be extended above the oil level and vented, if desired,but this is not necessary as the usual vent provided in the valve stem42 will suffice. In the event that it is desired to provide a device,such as shown in Figure 3 in which the flow rate can be varied, theparts can be threaded so as to permit adjustment of the elevation of theopening by threading or unthreading the member 45 as desired;

It is obvious that the invention may be embodied in many forms andconstructions within the scope of the claim and I wish it tobeunderstood that the particular forms shown are but a few of the manyforms. Various modifications and changes being possible, I do nototherwise limit myself in any way with respect thereto.

What is claimed is:

Means for controlling the flow of liquid fuel to maintaining a pilotflame over an indefinite period, which comprises a liquid receptacle,means to maintain liquid at a constant level in the receptacle, and anoutlet'from the chamber including a very small horizontal hole of theorder of .026 inch in diameter submerged a distance below the surface ofthe liquid in the order of a:

of an inch so as'to be under a small, but constant,

RALPH W. DE LANCEY.

